1. Field of the Invention
The present invention relates to gas extraction techniques for highly tempered gases, particularly for rotary kiln furnace exhaust gases in the production of cement, and is particularly concerned with safe and economical methods and apparatus for carrying out the extraction of gas samples.
2. Description of the Prior Art
With the aid of gas extraction apparatus, a representative test portion or sample may be withdrawn from the exhaust gas stream which participates in the combustion process in a rotary furnace, for analysis of gas constituents, in order to thereafter be able to adjudge and regulate the course of the combustion process.
It is known to provide a tubular probe or sampling device fixedly secured with a mounting flange through the wall of the inlet chamber to a rotary furnace, and to utilize such probe or device from time to time to draw off quantities of exhaust gas for analysis of the combustion process. As the probe or sampling device remains constantly in the heated gas chamber, it is disadvantageously subjected to all of the thermal, chemical and mechanical stresses occurring in the chamber. In addition, the continuous presence of the probe or sampling device in the inlet chamber is further disadvantageous, as it favors a deposit formation and bridge formation. It is in this connection both necessary and extraordinarily disadvantageous that the probe or sampling device, upon each cleaning of the heat exchanger, must be dismounted and again remounted with an appreciable expenditure of time. If removal is not undertaken, in a short time the probe or sampling device may be subjected to disturbances by means of material dropping down thereon from upper portions of the apparatus. Furthermore, upon dismounting of the probe or sampling device there always exists an appreciable danger of accident because of the weight of its tip. The reason for this lies both in the length of the probe or sampling device, as well as in the weight which is often increased on one side due to the disadvantageous effect of baking-on or caking of the material undergoing treatment. A further disadvantage resides in the fact that the probe or sampling device, due to a lack of a coolant, i.e., a cooling water supply, become disturbed in short order in the hot atmosphere of the inlet chamber due to the continuous flow of hot exhaust gases therethrough to a cooperating heat exchanger.